Shulchan_Arukh%2C_Orach_Chayim.119.1-2 with Connections
If one wanted to add in any of the middle blessings, something similar the blessing, one may add. How so? If one had a sick person, one asks for mercy for [that person] in the blessing of "Refa'einu" ["Heal us"]. If one needs a livelihood, one may ask for it in the "Blessing of the Years". And in [the blessing] of "Shomeya Tefilla" ["Who hears prayers"], one may ask for any of one's needs, for it includes all the requests. Gloss: And when one adds, one should begin the blessing and, after that, add, but one should not add and then begin the blessing (Tur 567). And according to Rabbeinu Yona, when one adds to the blessing something similar to that blessing, if one is adding it on behalf of all of Israel, one says it in plural language and not singular language, and one should only add at the end of the blessing and not the middle. And if one is asking specifically for one's own needs, for example: there is a sick person in one's home or one needs a livelihood, one can ask even in the middle of the blessing, as long as one does so in singular language and not plural language. And in the blessing of "Shomeya Tefilla" and similarly at the end of prayer, either right before "Yihyu l'ratzon" ["May it be acceptable before You"] or after it, one may ask in either singular language or plural language, whether it is specifically for one own needs or for of the public. יש מי שאומר שכשמוסיף בברכה לצורך יחיד לא יאריך: There is one [authority] who says that when one adds to a blessing for one's individual needs, one should not make it lengthy.
If one wanted to add in any of the middle blessings, something similar the blessing, one may add. How so? If one had a sick person, one asks for mercy for [that person] in the blessing of "Refa'einu" ["Heal us"]. If one needs a livelihood, one may ask for it in the "Blessing of the Years". And in [the blessing] of "Shomeya Tefilla" ["Who hears prayers"], one may ask for any of one's needs, for it includes all the requests. Gloss: And when one adds, one should begin the blessing and, after that, add, but one should not add and then begin the blessing (Tur 567). And according to Rabbeinu Yona, when one adds to the blessing something similar to that blessing, if one is adding it on behalf of all of Israel, one says it in plural language and not singular language, and one should only add at the end of the blessing and not the middle. And if one is asking specifically for one's own needs, for example: there is a sick person in one's home or one needs a livelihood, one can ask even in the middle of the blessing, as long as one does so in singular language and not plural language. And in the blessing of "Shomeya Tefilla" and similarly at the end of prayer, either right before "Yihyu l'ratzon" ["May it be acceptable before You"] or after it, one may ask in either singular language or plural language, whether it is specifically for one own needs or for of the public. יש מי שאומר שכשמוסיף בברכה לצורך יחיד לא יאריך: There is one [authority] who says that when one adds to a blessing for one's individual needs, one should not make it lengthy.